20NA123

Service Bulletin
Bulletin No.:
20-NA-123
Date:
June, 2020
INFORMATION
Subject:
Brand:
Cadillac
Chevrolet
Malfunction Indicator Lamp (MIL) Illuminated, DTCs U1961, U1983 Set
Model:
Model Year:
Breakpoint:
from
to
from
to
2020
2020
—
—
Engine:
Transmission:
—
—
CT4
CT5
Corvette
Involved Region or Country
North America, Middle East, GM Korea Company, Israel, Palestine
Condition
Some customers may comment that the Malfunction Indicator Lamp (MIL) is illuminated.
Technicians may find the following DTCs set:
• U1961 - Control Module Security Hardware Internal Malfunction
• U1983 - Serial Data Gateway Module Security Hardware Internal Malfunction
Cause
This condition may be caused by not clearing the DTCs and also allowing a sleep cycle
after programming or serial data authentication configuration.
Correction
Clear the DTCs and allow the vehicle to go into sleep mode.
Version
1
Modified
Released June 02, 2020
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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